The use of prosthetic liners adapted to provide an interface between a residual limb of an amputee and a hard socket to which a prosthetic device is secured is recognized in the art generally, as exemplified by U.S. Pat. No. 4,923,474.
Many conventional prosthetic liners are suspension liners adapted to secure the residual limb within the hard socket once the residual limb and liner are inserted into the socket in a close-fitting relationship. The distal region of these liners may include one or more seal elements arranged to engage the inner side of the socket and isolate the distal end area of the socket from atmosphere. Upon application of a pulling force on the liner relative to the socket, a suction is created in the distal end of the socket tending to retain the liner within the socket. Appropriate devices are usually provided to enable expulsion of air between the distal end of the liner and the hard socket, and to isolate the distal end of the hard socket from the atmosphere after the liner with a residual limb has been fully inserted within the hard socket.
According to a variation, the liner can be arranged as a locking liner provided with an umbrella at its distal end and a threaded socket for receiving a prosthetic securing pin member which then extends through an axial opening in the distal end of the hard socket.
While several prosthetic liner products exist, they have a number of drawbacks. For instance, anatomical variations in a residual limb tend to complicate and even compromise the seal formed between existing liners and the interior of the hard socket. In addition, radial movement or tilting of the residual limb within the socket is known to break or compromise the seal formed between the liner and the hard socket. With this loss of isolation, the connection between the residual limb and the hard socket can be unpredictable and/or inadequate, causing the user discomfort, grief and even injury.
There is thus a need for a prosthetic liner that provides a more reliable and comfortable connection between a residual limb and a prosthetic socket.